JP7013351B2 - Thermoplastic resin foam sheet and molded body - Google Patents

Description

The present invention relates to a thermoplastic resin foam sheet and a molded product.

A foamed sheet (thermoplastic resin foamed sheet) in which a thermoplastic resin such as a polystyrene resin is foamed is widely used as a raw material for a container or the like for accommodating food or the like. The molded body of the thermoplastic resin foam sheet is lightweight, has high heat insulating properties, has high strength, and is resistant to cracking.
There are various demands for molded products of thermoplastic resin foam sheets, such as improvement of heat resistance, improvement of weather resistance, diversification of color, and reduction of odor. In the thermoplastic resin foam sheet, it is necessary to improve the moldability and the like while meeting the above-mentioned demands. In order to satisfy these demands, there is a technique for blending inorganic particles into a thermoplastic resin foam sheet. However, when a thermoplastic resin foam sheet containing inorganic particles is manufactured, there is a problem that productivity is easily impaired.

For example, a container formed from a foamed sheet made of a polystyrene resin does not have sufficiently high heat resistance. Therefore, a container formed from a general-purpose polystyrene-based resin foam sheet is easily deformed when heated by a microwave oven or the like. To solve this problem, there is a thermoplastic resin foam sheet containing a polyphenylene ether-based resin.
The thermoplastic resin foam sheet emits a unique odor depending on the type of resin. In order to suppress this odor, a thermoplastic resin foam sheet containing a deodorant such as silica particles has been proposed. However, when the inorganic particles of the deodorant are mixed with the thermoplastic resin foamed sheet, the equipment for manufacturing the thermoplastic resin foamed sheet is clogged, and the productivity is easily impaired. In addition, even if the manufacturing equipment is not clogged, if agglomerates of inorganic particles adhere to the openings of the die, scratches such as dents may occur on the surface of the obtained foamed sheet. In response to these problems, Patent Document 1 describes a polystyrene-based resin composition containing a hydrotalcite calcined product, a silica-based deodorant, a fatty acid metal salt, a glycerin fatty acid ester, and a polystyrene-based resin in a specific ratio. Things have been proposed.

Japanese Patent Application Laid-Open No. 2015-067705

However, the conventional technique cannot sufficiently prevent the clogging of the manufacturing equipment due to the inorganic particles. In addition, the conventional technique cannot sufficiently prevent the appearance of the thermoplastic resin foam sheet from being poor.
Therefore, an object of the present invention is a thermoplastic resin foamed sheet that enhances productivity and is less likely to cause poor appearance.

[1] It has a foam layer and
The foam layer contains a thermoplastic resin and a group of inorganic particles.
The group of inorganic particles contains the first group of inorganic particles.
A thermoplastic resin foamed sheet having an average specific surface area of 1.0 m ² / g or more and less than 200 m ² / g in the group of the first inorganic particles.
[2] The thermoplastic resin foam sheet according to [1], wherein the content of the first inorganic particles is 10 to 100 parts by mass with respect to 100 parts by mass of the group of the inorganic particles.
[3] The thermoplastic resin foamed sheet according to [1] or [2], wherein the bulk density of the group of the first inorganic particles is 0.02 to 1.0 g / cm ³ .
[4] The primary particles in the group of the first inorganic particles are described in any one of [1] to [3], wherein the ratio represented by the mode diameter / median diameter is 0.1 or more and less than 1.0. Thermoplastic resin foam sheet.
[5] The thermoplastic resin foam sheet according to any one of [1] to [4], wherein the standard deviation of the median diameter of the primary particles of the first group of inorganic particles is 0.3 μm or more.
[6] The thermoplastic resin foam sheet according to any one of [1] to [5], wherein the thermoplastic resin contains a polystyrene-based resin or contains a polystyrene-based resin and a polyphenylene ether-based resin.
[7] The thermoplastic resin contains a polyphenylene ether-based resin and contains.
The thermoplastic resin foam sheet according to any one of [1] to [6], wherein the content of the polyphenylene ether-based resin is 10 to 50 parts by mass with respect to 100 parts by mass of the thermoplastic resin.
[8] Any of [1] to [7], wherein the group of the inorganic particles contains at least one selected from a bubble regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant and a deodorant. The thermoplastic resin foam sheet described in Crab.
[9] The heat according to any one of [1] to [8], wherein the content of the group of the first inorganic particles is 0.05 to 20 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Plastic resin foam sheet.

[10] A molded product obtained by molding the thermoplastic resin foam sheet according to any one of [1] to [9].
[11] The molded product according to [10], which is a container for food.

In addition, the present invention has the following aspects.
[12] The first group of inorganic particles contains a group of particles of a hydrotalcite calcined product.
The thermoplastic resin foam sheet according to [1], wherein the content of the particle group of the hydrotalcite calcined product is 40 to 100 parts by mass with respect to 100 parts by mass of the total amount of the group of the first inorganic particles.
[13] The first group of inorganic particles contains the group of particles of the hydrotalcite calcined product and the group of particles of silica.
The thermoplastic resin foam sheet according to [12], wherein the mass ratio represented by [particle group of hydrotalcite calcined product] / [silica particle group] is 4/6 to 9/1.
[14] The thermoplastic resin foaming according to [12] or [13], wherein the content of the first group of inorganic particles is 10 to 100 parts by mass with respect to 100 parts by mass of the group of inorganic particles. Sheet.
[15] The thermoplastic resin foam sheet according to any one of [12] to [14], wherein the bulk density of the particles of the hydrotalcite calcined product is 0.02 to 1.0 g / cm ³ .
[16] The primary particles of the particle group of the hydrotalcite fired product are any of [12] to [15], wherein the ratio represented by the mode diameter / median diameter is 0.1 or more and less than 1.0. The thermoplastic resin foam sheet described.
[17] The thermoplastic resin foam sheet according to any one of [12] to [16], wherein the median diameter of the primary particles of the particle group of the hydrotalcite calcined product is 0.05 to 30 μm.
[18] The thermoplastic resin foam sheet according to any one of [12] to [17], wherein the standard deviation of the median diameter of the primary particles of the particle group of the hydrotalcite fired product is 0.3 μm or more.

According to the thermoplastic resin foam sheet of the present invention, productivity is increased and appearance defects are less likely to occur.

It is a schematic diagram which shows an example of the manufacturing apparatus of a thermoplastic resin foam sheet.

(Thermoplastic resin foam sheet)
The thermoplastic resin foamed sheet of the present invention (hereinafter, may be simply referred to as “foamed sheet”) has a foamed layer containing a thermoplastic resin and a group of inorganic particles.
The foamed sheet may have a single-layer structure consisting of only a foamed layer, or may have a multi-layered structure having a non-foamed layer on one side or both sides of the foamed layer.

The thickness of the foamed sheet can be determined in consideration of the intended use, and is preferably 500 to 4000 μm, more preferably 1000 to 2500 μm, for example.

[Foam layer]
The foamed layer is a layer formed by foaming a resin composition containing a resin and a group of inorganic particles. The resin contains a thermoplastic resin. The foamed sheet exhibits heat insulating properties by having a foamed layer.

The thermoplastic resin is, for example, a polystyrene-based resin (hereinafter, may be referred to as a component (A)), a polyphenylene ether-based resin (hereinafter, may be referred to as a component (B)), a polyolefin-based resin, or the like.

The component (A) is, for example, a homopolymer of a styrene-based monomer such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromostyrene, or a copolymer thereof; A copolymer of a styrene-based monomer as a main component (50% by mass or more) and a styrene-based monomer and a vinyl monomer polymerizable on the styrene-based monomer: a copolymer of a styrene-based monomer and a rubber component such as butadiene, or a styrene-based monomer. Is a so-called high-impact polystyrene, which is a homopolymer of the above, a copolymer thereof, a copolymer of a styrene-based monomer and a vinyl monomer, and a mixture or a polymer of a diene-based rubber-like polymer.
Vinyl monomers that can be polymerized with styrene-based monomers include, for example, alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and cetyl (meth) acrylate, (meth) acrylonitrile, and dimethyl. It is a bifunctional monomer such as maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, alkylene glycol dimethacrylate and the like. These vinyl monomers may be used alone or in combination of two or more.
Examples of the diene-based rubber-like polymer include polybutadiene, styrene-butadiene copolymer, ethylene-propylene-non-conjugated diene three-dimensional copolymer, and acrylonitrile-butadiene-styrene copolymer.
These components (A) may be used alone or in combination of two or more.

The component (A) may be a polystyrene-based resin that is not a recycled raw material, such as a commercially available polystyrene-based resin or a polystyrene-based resin newly prepared by a method such as a suspension polymerization method, or may be a polystyrene-based resin that is a recycled raw material. ..
The recycled raw material is a used polystyrene-based resin foam molded product. Recycled raw materials include fish boxes, cushioning materials for home appliances, trays for food packaging, etc., which are collected and recycled by a limonene melting method or a heating volume reduction method. In addition, the recycled raw materials that can be used are non-foamed polystyrene resin moldings that are separately collected from home appliances (for example, TVs, refrigerators, washing machines, air conditioners, etc.) and office equipment (for example, copiers, facsimiles, printers, etc.). The body may be crushed, melt-kneaded and repelletized.

The content of the component (A) in the foam sheet is preferably 50 to 90 parts by mass, more preferably 60 to 90 parts by mass, and 70 to 90 parts by mass with respect to 100 parts by mass of the thermoplastic resin (resin constituting the foam layer). Parts by mass are more preferred. When the content of the component (A) is at least the above lower limit value, the foamed sheet becomes stiff and the molded product can be handled more easily. When the content of the component (A) is not more than the above upper limit value, the characteristics of the other resin are likely to be exhibited when the other resin is blended.

The foamed layer exhibits excellent heat resistance by containing a polyphenylene ether-based resin (component (B)).

Examples of the component (B) include compounds represented by the following formula (I).

In the formula (I), R ¹ and R ² each independently represent an alkyl group or a halogen atom having 1 to 4 carbon atoms. Examples of the halogen atom include fluorine, chlorine, bromine and the like.
In the formula (I), n is a positive integer representing the degree of polymerization. n is, for example, usually 10 to 5000.

Examples of the component (B) represented by the formula (I) include poly (2,6-dimethylphenylene-1,4-ether), poly (2,6-diethylphenylene-1,4-ether), and poly. (2,6-dichlorophenylene-1,4-ether) and the like can be mentioned.

The content of the component (B) in the foam layer is preferably 10 to 50 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin. When the content of the component (B) is at least the above lower limit value, the heat resistance of the foamed sheet is further enhanced. When the content of the component (B) is not more than the above upper limit value, the foamed sheet becomes stiff and the molded product can be handled more easily.

The polyolefin-based resin (hereinafter, may be referred to as the component (C)) contains, for example, a homopolymer of an olefin-based monomer such as ethylene or propylene, a copolymer thereof, or an olefin-based monomer as a main component, and the olefin-based monomer. It is a copolymer with a vinyl monomer that can be polymerized.

The content of the component (C) in the foam layer is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and may be 0 parts by mass with respect to 100 parts by mass of the thermoplastic resin. When the content of the component (C) is not more than the above upper limit value, the foamed sheet becomes stiff and the molded product can be handled more easily.

These thermoplastic resins may be used alone or in combination of two or more.
Among them, the thermoplastic resin preferably contains a polystyrene-based resin or a polyphenylene ether-based resin, or preferably contains a polystyrene-based resin and a polyphenylene-based resin. Among them, the thermoplastic resin preferably contains a polystyrene-based resin, or preferably contains a polystyrene-based resin and a polyphenylene ether-based resin, and more preferably contains a polystyrene-based resin and a polyphenylene ether-based resin.

The thermoplastic resin may contain a rubber component. Since the foam layer contains a rubber component, it has excellent impact resistance. In addition, it is easy to prevent breakage during the production of the foam layer or the foam sheet or the production of the molded product.

The rubber content in the foam layer may be, for example, a rubber content derived from high-impact polystyrene used as the component (A), or a rubber content derived from a diene-based rubber-like polymer blended separately from the component (A). But it may be.
Examples of the diene-based rubber-like polymer compounded separately from the component (A) include polybutadiene, styrene-butadiene copolymer, ethylene-propylene-non-conjugated diene three-dimensional copolymer, and acrylonitrile-butadiene-styrene copolymer. And so on.

The content of the rubber content in the foam layer is determined in consideration of the content of the component (B), and is preferably 0.2 to 2.0 parts by mass, for example, 0. 3 to 1.8 parts by mass is more preferable. When the rubber content is equal to or higher than the above lower limit, the impact resistance is further enhanced. When the content of the rubber content is not more than the above upper limit value, the foamed layer has an appropriate hardness, and the strength of the molded product obtained by molding is further increased.

The content of the rubber content in the thermoplastic resin with respect to 100 parts by mass of the component (B) is preferably 1.0 to 10.0 parts by mass, more preferably 1.5 to 8.0 parts by mass, and 2.0 to 6 parts. .0 parts by mass is more preferable. When the content of the rubber content is at least the above lower limit value, the impact resistance of the foamed sheet is further enhanced, and it becomes more difficult to break during manufacturing. When the content of the rubber content is not more than the above upper limit value, the heat resistance of the foamed sheet is further enhanced.

The foam layer contains a group of inorganic particles. By containing a group of inorganic particles, the foam layer exerts an effect derived from the inorganic particles.

The group of inorganic particles is, for example, at least one selected from a bubble regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant and a deodorant. As the group of inorganic particles, a bubble adjusting agent and a deodorant are preferable.

The bubble adjusting agent is, for example, a mixture of inorganic powders such as talc and silica. These bubble adjusting agents increase the closed cell ratio of the foam layer and easily form the foam layer.

The stabilizer is, for example, a calcium-zinc-based heat stabilizer, a tin-based heat stabilizer, a lead-based heat stabilizer, or the like.

The ultraviolet absorber is, for example, a cesium oxide-based ultraviolet absorber, a titanium oxide-based ultraviolet absorber, or the like.

Antioxidants are, for example, cerium oxide, cerium oxide / zirconia solid solution, cerium hydroxide, carbon, carbon nanotubes, titanium oxide, fullerenes and the like.

The colorant is, for example, titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine, cobalt blue, fired pigment, metallic pigment, mica, pearl pigment, zinc flower, precipitated silica, cadmium red and the like.
These colorants may be used alone or in combination of two or more. When the foamed sheet of the present invention is used for a container for food, it is preferable to select a product registered by the Sanitary Council such as polyolefin from the above colorants.

The deodorant is, for example, silica, zeolite, zirconium phosphate, hydrotalcite calcined product and the like.

The group of inorganic particles includes the group of first inorganic particles.
The first group of inorganic particles is a group of inorganic particles having an average specific surface area of 1.0 m ² / g or more and less than 200 m ² / g.
The foam layer is manufactured by an extrusion molding method as in the manufacturing method described later. In this extrusion manufacturing method, when the inorganic particles aggregate to become large secondary particles, the secondary particles are likely to be clogged with a die of an extrusion molding machine or the like. In addition, when large secondary particles adhere to the inside of the flow path (for example, the opening of the die), the attached secondary particles form streaks on the surface of the foam layer.
Since the first group of inorganic particles is less likely to aggregate in the resin composition, it is less likely to cause clogging of the manufacturing equipment when the foamed layer is manufactured. In addition, since the first group of inorganic particles is difficult to aggregate, it is difficult to form streaks that impair the appearance of the foamed sheet even if they adhere to a die or the like.
Further, by blending the group of the first inorganic particles with the resin composition, even when the group of the second inorganic particles described later is blended with the resin composition, the second inorganic particles can be less likely to aggregate with each other.

The average specific surface area of the first group of inorganic particles is preferably 10 to 150 m ² / g, more preferably 30 to 150 m ² / g, even more preferably 40 to 150 m ² / g, and particularly preferably 100 to 150 m ² / g. It is preferably 100 to 130 m ² / g, most preferably 100 to 130 m 2 / g. When the average specific surface area is within the above range, it is possible to better prevent the particles from aggregating with each other. In addition, if the average specific surface area is within the above range, the enlargement of the particle size of the secondary particles of the inorganic particles can be better suppressed.
The average specific surface area is the average value of the BET specific surface areas of 100 samples measured by the BET method.

The bulk density of the first inorganic particles is preferably 0.02 to 1.0 g / cm ³ , more preferably 0.05 to 0.8 g / cm ³ , and even more preferably 0.1 to 0.7 g / cm ³ . .. When the bulk density is at least the above lower limit value, the mixing efficiency with the resin composition is increased, and the handling becomes easier. When the bulk density is not more than the above upper limit value, the density difference with the resin composition becomes small, and it becomes easier to disperse. The bulk density is measured by the following measuring method.
<Measurement method>
The sample is filled in a metal container having a volume of 25 cm ³ and having an opening at the upper end. At this time, the sample is filled in a metal container in 2 to 3 minutes using a quantitative feeder or the like. Scrape the raised sample from the opening of the metal container. The mass of the sample in the metal container is measured and divided by the volume (25 cm ³ ) to obtain the bulk density.

The median diameter of the primary particles of the first group of inorganic particles (hereinafter, may be referred to as “primary median diameter”) is preferably 0.05 to 30 μm, more preferably 0.1 to 20 μm, and more preferably 0.15 to 10 μm. Is more preferable, 2 to 6 μm is particularly preferable, and 3 to 5 μm is most preferable. When the primary median diameter is at least the above lower limit value, it is possible to better suppress the generation of secondary particles and better suppress the enlargement of the particle size of the generated secondary particles. When the primary median diameter is not more than the above upper limit value, clogging of dies and the like is less likely to occur.
The primary median diameter is a volume average particle diameter (50% by mass particle diameter) determined by a laser diffraction method.

The distribution of the primary median diameter is preferably broad. For unknown reasons, if the distribution of the primary median diameter is broad, the inorganic particles are more likely to aggregate.
Therefore, the standard deviation of the primary median diameter is preferably 0.3 μm or more, more preferably 0.3 to 0.7 μm, further preferably 0.4 to 0.6 μm, and particularly preferably 0.45 to 0.55 μm.

The mode diameter of the primary particles of the first group of inorganic particles (hereinafter, may be referred to as “primary mode diameter”) is preferably 0.5 to 10 μm, more preferably 0.8 to 7 μm, and 0.9 to 4 Is more preferable, and 1 to 2 μm is particularly preferable.
The primary mode diameter is a re-frequent value (volume distribution) obtained by the laser diffraction method.
The primary median diameter and the primary mode diameter are measured by the following methods. The object to be measured is dispersed in 0.2% by mass of a sodium hexametaphosphate solvent. The primary particle diameter of this dispersion is measured with a laser diffraction type distribution measuring device (SALD-2200, manufactured by Shimadzu Corporation) to obtain a primary median diameter and a primary mode diameter.

The ratio represented by [primary mode diameter] / [primary median diameter] in the first group of inorganic particles (hereinafter, may be referred to as “Mo / Me ratio”) is preferably 0.1 or more and less than 1.0. , 0.1 to 0.6 is more preferable, and 0.2 to 0.5 is even more preferable. When the Mo / Me ratio is equal to or higher than the above lower limit value, clogging of dies and the like is less likely to occur. When the Mo / Me ratio is not more than the above upper limit value, the generation of secondary particles is further suppressed, and clogging of dies and the like is less likely to occur.

The first group of inorganic particles is preferably one or more selected from a bubble regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant and a deodorant.
Examples of the material of the first group of inorganic particles include hydrotalcite calcined products, silica and the like. Among them, the material of the first group of inorganic particles is preferably a hydrotalcite calcined product or silica, and more preferably a hydrotalcite calcined product. If it is a hydrotalcite fired product, even a group of first inorganic particles can exhibit a sufficient deodorizing effect.
The first group of inorganic particles may be one kind alone or a combination of two or more kinds. From the viewpoint of complementing different functions, the first group of inorganic particles is preferably a combination of two or more kinds, and more preferably a combination of a hydrotalcite calcined product and silica.

Hydrotalcite is a type of naturally occurring clay mineral. Generally, hydrotalcite is a double hydroxide represented by the following formula (11).
M ¹ _8-x M ² _x (OH) ₁₆ CO ₂ · nH ₂ O… (11)
In the formula (11), M ¹ is any one of Mg ²⁺ , Fe ²⁺ , Zn ²⁺ , Ca ²⁺ , Li ²⁺ , Ni ²⁺ , Co ²⁺ , and Cu ²⁺ . M ² is any of Al ³⁺ , Fe ³⁺ , and Mn ²⁺ . x is preferably 2 to 5. n is an integer of 0 or more.

The hydrotalcite may be a synthetic product. The synthetic product of hydrotalcite is obtained by, for example, the following production method.
An aqueous suspension of basic magnesium carbonate particles and an aqueous suspension of aluminum hydroxide are mixed to obtain a mixed suspension. At this time, the ratio (Mg / Al) of the magnesium atom and the aluminum atom is set to a predetermined ratio (for example, 2.6 to 3.2). Caustic alkali is added to the mixed suspension to obtain a reaction solution having a pH of 8.5 to 11.5. The caustic alkali is sodium hydroxide, potassium hydroxide, ammonium hydroxide and the like. The obtained reaction solution is heated at, for example, 50 to 100 ° C. for 0.5 to 20 hours for aging. The hydrotalcite particles are then solid-liquid separated from the mixed suspension. The separated hydrotalcite particles are washed, dehydrated and then dried to obtain a synthetic hydrotalcite.
Synthetic calcined products can be used in the same manner as naturally produced calcined products.
Hydrotalcite releases adsorbed water, water of crystallization, etc. when heated. When hydrotalcite is calcined to 200 ° C. or higher, adsorbed water is released, and when calcined to 400 ° C. or higher (for example, 550 ° C.), carbonate roots and hydroxyl groups are desorbed.

The hydrotalcite calcined product is obtained by calcining hydrotalcite at the above temperature. As the hydrotalcite calcined product, for example, a compound represented by the following formula (12) is preferable.
Mg _0.7 Al _0.3 O _1.15 ... (12)

The content of the first group of inorganic particles in the foam layer is preferably 10 to 100 parts by mass, more preferably 20 to 100 parts by mass, and 40 to 100 parts by mass with respect to 100 parts by mass of the total amount of the group of inorganic particles. More preferably, 50 to 100 parts by mass is particularly preferable, and 60 to 100 parts by mass is most preferable. When the content of the group of the first inorganic particles is at least the above lower limit value, clogging of dies and the like can be better prevented, and the appearance of the foamed sheet can be improved.

The total amount of the group of the first inorganic particles in the foam layer is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and 0.3 to 0.3 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin. 5.0 parts by mass is more preferable. When the total amount of the first group of inorganic particles is not less than the above lower limit, the aggregation of the group of inorganic particles can be suppressed more satisfactorily. When the total amount of the first group of inorganic particles is not more than the above upper limit value, clogging to the die or the like can be better prevented and the appearance of the foamed sheet can be improved.

When the first group of inorganic particles contains a bubble adjusting agent, the content of the bubble adjusting agent in the foam layer is preferably 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin. 0.02 to 3.0 parts by mass is more preferable, and 0.03 to 2.0 parts by mass is further preferable.

When the first group of inorganic particles contains a bubble conditioner and a deodorant, the total content of the first group of inorganic particles is 10 with respect to 100 parts by mass of the total amount of the group of inorganic particles. ~ 100 parts by mass is preferable, 20 to 200 parts by mass is more preferable, 30 to 100 parts by mass is further preferable, 40 to 100 parts by mass is further preferable, 50 to 100 parts by mass is particularly preferable, and 60 to 100 parts by mass is the most. preferable.

When the group of the first inorganic particles contains the particle group of the hydrotalcite calcined product, the content of the particle group of the hydrotalcite calcined product is based on 100 parts by mass of the total amount of the group of the first inorganic particles. 40 to 100 parts by mass is preferable, 50 to 100 parts by mass is more preferable, and 60 to 100 parts by mass is further preferable. When it is at least the above lower limit value, the odor of the thermoplastic resin foam sheet can be further suppressed.
Further, when the group of the first inorganic particles has both the hydrotalcite calcined product and the group of the other first inorganic particles, 40 with respect to 100 parts by mass of the total amount of the group of the first inorganic particles. It is preferably up to 90 parts by mass, preferably 40 to 80 parts by mass, preferably 40 to 70 parts by mass, and particularly preferably 50 to 70 parts by mass.

When the first group of inorganic particles contains a hydrotalcite calcined product and silica, the content of the first inorganic particles is 10 to 100 parts by mass with respect to 100 parts by mass of the total amount of the group of inorganic particles. Preferably, 20 to 200 parts by mass is more preferable, 30 to 100 parts by mass is further preferable, 40 to 100 parts by mass is further preferable, 50 to 100 parts by mass is particularly preferable, and 60 to 100 parts by mass is most preferable.
When the first group of inorganic particles contains a group of particles of hydrotalcite calcined product and a group of particles of silica, the mass ratio represented by [particle group of hydrotalcite calcined product] / [particle group of silica]. (Hereinafter, sometimes referred to as "H / S ratio") is preferably 4/6 to 9/1, more preferably 5/5 to 9/1, and even more preferably 5/5 to 7/3. When the H / S ratio is within the above range, the productivity can be further increased and the occurrence of poor appearance can be further suppressed.

When the group of the first inorganic particles contains the particle group of the hydrotalcite calcined product, the particle group of the hydrotalcite calcined product is the standard of the primary median diameter, the primary mode diameter, the Mo / Me ratio and the median diameter described above. It is preferable to satisfy at least one of the deviations.

The group of inorganic particles may contain a second group of inorganic particles. The second group of inorganic particles is a group of inorganic particles having an average specific surface area of 200 m ² / g or more.

The larger the average specific surface area of the second group of inorganic particles, the better the function required for the second group of inorganic particles can be exhibited.
The average specific surface area of the second group of inorganic particles is preferably 200 to 1000 m ² / g, more preferably 250 to 900 m ² / g, and even more preferably 300 to 850 m ² / g.

The average particle size of the second group of inorganic particles is preferably 0.1 to 50 μm, more preferably 0.3 to 40 μm, and even more preferably 0.5 to 30 μm. When the average particle diameter of the second group of inorganic particles is equal to or greater than the above lower limit, the function of the second group of inorganic particles is more likely to be exhibited. When the average particle size of the group of the second inorganic particles is not more than the above upper limit value, clogging to the die or the like can be better prevented and the appearance of the foamed sheet can be improved.

When the group of inorganic particles contains the group of the second inorganic particles, the content of the group of the second inorganic particles in the foamed layer is 10 to 80 mass by mass with respect to 100 parts by mass of the total amount of the group of the inorganic particles. Parts are preferable, 20 to 70 parts by mass are more preferable, 30 to 60 parts by mass are further preferable, and 30 to 50 parts by mass are particularly preferable. When the content of the second inorganic particles is at least the above lower limit value, the function of the group of the second inorganic particles is more likely to be exhibited. When the content of the group of the second inorganic particles is not more than the above upper limit value, clogging to the die or the like can be better prevented and the appearance of the foamed sheet can be improved.

The group of inorganic particles may contain a group of third inorganic particles having an average specific surface area of less than 10 m ² / g.

The total amount of the group of inorganic particles in the foam layer is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and 0.3 to 5.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Parts by mass are more preferred. When the total amount of the group of inorganic particles is at least the above lower limit value, the function of the group of inorganic particles can be exhibited better. When the total amount of the group of inorganic particles is not more than the above upper limit value, clogging to the die or the like can be better prevented and the appearance of the foamed sheet can be improved.

The foam layer can contain optional components such as foam nucleating agents, nucleating agents, deodorants, ultraviolet absorbers, antioxidants, lubricants, flame retardants, and additives such as antistatic agents.

The type of optional additive is determined in consideration of the physical characteristics required for the foamed sheet. The above-mentioned additives may be used alone or in combination of two or more.

The thickness of the foamed layer can be determined in consideration of the use of the foamed sheet and the like. For example, when the foamed sheet is used for a container for food, the thickness of the foamed sheet is preferably 500 to 4000 μm, more preferably 1000 to 2500 μm.
The thickness is a value obtained by the following method. The thickness of the foam layer at any 10 points in the TD direction is measured with a microgauge. The measured values at 10 points are averaged to obtain the thickness of the foam layer.

The density (overall density) of the entire foam layer is, for example, preferably 0.05 to 0.25 g / cm ³ , more preferably 0.06 to 0.22 g / cm ³ . When the overall density is equal to or higher than the above lower limit, the strength of the foam layer can be further improved. When the overall density is not more than the above upper limit value, the heat insulating property of the foamed sheet can be further improved.

The average bubble diameter of the foam layer is preferably 80 to 450 μm, for example. The average bubble diameter of the foam layer is a value measured according to the method described in ASTM D2842-69.

The closed cell ratio of the foam layer is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and may be 100%. The closed cell ratio of the foam layer is a value measured by the method described in JIS K7138: 2006 "Hard foamed plastic-How to determine open cell ratio and closed cell ratio".

The foamed sheet may have a non-foamed layer on one or both sides of the foamed layer.
The resin constituting the non-foamed layer is not particularly limited, and examples thereof include resins similar to the resin constituting the foamed layer.
The resin constituting the non-foamed layer may be the same as or different from the resin constituting the foamed layer.

The thickness of the non-foamed layer is determined in consideration of the use of the foamed sheet and the like, and is preferably 50 to 300 μm, more preferably 70 to 200 μm, for example. When the thickness of the foamed layer is at least the above lower limit value, the strength of the foamed sheet can be further improved. When the thickness of the non-foamed layer is not more than the above upper limit, the weight of the foamed sheet can be reduced.

(Production method)
The foamed sheet is manufactured by a conventionally known manufacturing method.
The method for manufacturing a foamed sheet will be described by taking as an example a method for manufacturing a single-layer foamed sheet.
The foamed sheet manufacturing apparatus 1 of FIG. 1 is an apparatus for obtaining a foamed sheet by extrusion molding. The manufacturing apparatus 1 includes an extruder 10, a foaming agent supply source 18, a circular die 20, a mandrel 30, and two winders 40.
The extruder 10 is a so-called tandem extruder. The extruder 10 includes a first extruder 11 and a second extruder 12 connected to the first extruder 11 by a pipe 16. The first extrusion portion 11 includes a hopper 14. A foaming agent supply source 18 is connected to the first extrusion portion 11.
A circular die 20 is connected to the second extrusion section 12. A mandrel 30 provided with a cutter 32 is provided downstream of the circular die 20. A cooling blower (not shown) is provided between the circular die 20 and the mandrel 30.

The raw material constituting the foam layer is charged from the hopper 14 into the first extrusion section 11. The raw material input from the hopper 14 is a resin constituting the foam layer, a group of inorganic particles, and an optional component to be blended as needed.
In the first extrusion section 11, the raw materials are mixed while being heated to an arbitrary temperature to form a resin melt, and the foaming agent is supplied from the foaming agent supply source 18 to the first extrusion section 11, and the foaming agent is added to the resin melt. To obtain a resin composition.
The heating temperature is appropriately determined within a range in which the resin is melted and arbitrary components are not denatured in consideration of the type of resin and the like.

The foaming agent is, for example, a hydrocarbon such as propane, butane, or pentane; a halogenated hydrocarbon such as tetrafluoroethane, chlorodifluoroethane, or difluoroethane. Of these, butane is preferable as the foaming agent. Butane may be normal butane or isobutane alone, or may be a combination of normal butane and isobutane.
These foaming agents may be used alone or in combination of two or more.
The blending amount of the foaming agent is determined in consideration of the type of the foaming agent, the total density required for the foamed sheet, and the like. The content of the foaming agent is preferably 1.0 to 7.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

The resin composition is supplied from the first extrusion section 11 to the second extrusion section 12 via the pipe 16 and further mixed. Then, the resin composition is cooled to an arbitrary temperature and then guided to the resin flow path in the circular die 20.
The resin composition guided to the resin flow path is extruded from the circular die 20 and the foaming agent foams to form a cylindrical foam sheet 2a.
The cylindrical foam sheet 2a is guided to the mandrel 30 while being blown with cooling air blown from the cooling blower. The cylindrical foam sheet 2a passes through the outer surface of the mandrel 30, is cooled to an arbitrary temperature, and is cut into two by a cutter 32 to become the foam sheet 2. The foamed sheet 2 is wound around the guide roll 42 and the guide roll 44, respectively, and wound up by the winder 40 to become the foamed sheet roll 4.
In this way, a foamed sheet having a single-layer structure can be obtained.

Examples of the method for forming the non-foamed layer include a method in which a foamed layer is obtained by the above-mentioned manufacturing method and a non-foamed layer is formed on the surface of the foamed layer by the T-die method.

(Molded body)
The molded product of the present invention is formed by molding the above-mentioned foamed sheet of the present invention.
Examples of the molded body include trays having a perfect circular shape, an elliptical shape, a semicircular shape, a polygonal shape, a fan shape, etc., a bowl-shaped container, a container such as a bottomed cylinder or a bottomed square cylinder, and a container for natto. Various containers such as containers with lids; lids and the like attached to the container body can be mentioned.
As the use of these containers, for example, food products are preferable.

The thickness of the molded product is determined in consideration of the intended use and the like, and is preferably 500 to 4000 μm, more preferably 1000 to 2500 μm, for example.
The overall density of the foamed layer in the molded product is determined in consideration of the application and the like, and is the same as the overall density of the foamed layer in the foamed sheet.
The molded product is manufactured by a conventionally known manufacturing method, and examples thereof include a heat molding method in which a foamed sheet is sandwiched between a female mold and a male mold while being heated at an arbitrary temperature.

As described above, according to the foamed sheet of the present invention, since it contains a group of inorganic particles, it exhibits the function of the group of inorganic particles. In addition, according to the foamed sheet of the present invention, since the group of inorganic particles including the group of the first inorganic particles is contained, the group of inorganic particles is less likely to aggregate. Therefore, the foamed sheet of the present invention enhances productivity and is less likely to cause poor appearance.

(Raw materials used)
-PS: Polystyrene resin, MW = 323 x 103 ^, manufactured by DIC Corporation, product name "XC-515".
-PPE: Polyphenylene ether resin, manufactured by SABIC, product name: "Noril EFN4230".
-Bubble conditioner: A talc-containing resin composition (containing 40% by mass of talc (average specific surface area 10 to 40 m ² / g), manufactured by Toyo Styrene Co., Ltd., product name "DSM1401A").

-Particle group I-1: Hydrotile site fired product. Prepared to the standard deviation of the average specific surface area, primary median diameter, primary mode diameter, and particle diameter shown in Table 1.
-Particle group I-2: Silica, prepared to the standard deviation of the average specific surface area, primary median diameter, primary mode diameter, and particle diameter shown in Table 1.
-Particle group II-1: Zeolites, prepared to the average specific surface area and primary median diameter shown in Table 1.
-Particle group II-2: Synthetic silica, prepared to the average specific surface area and primary median diameter shown in Table 1.
-Particle group II-3: Hydrotalcite fired product. Prepared to the standard deviation of the average specific surface area, primary median diameter, primary mode diameter, and particle diameter shown in Table 2.

(Examples 1 to 16, Comparative Examples 1 to 4)
Using the same manufacturing equipment as the foamed sheet manufacturing apparatus of FIG. 1, a foamed sheet was obtained as follows.
A group of PS, PPE, bubble conditioner and inorganic particles were mixed according to the compositions of Tables 1-5.
A mixture of raw materials was supplied from the hopper to the first mixing portion (screw diameter: 115 mm), heated at a maximum temperature of 300 ° C., and melt-kneaded to obtain a resin melt.
A foaming agent (isobutane: normal butane = 70:30 (mass ratio) mixture) was supplied to the first extruded portion, and the resin melt and the foaming agent were mixed to obtain a resin composition. The blending amount of the foaming agent was the mass part shown in Table 1 with respect to 100 parts by mass of the thermoplastic resin.
The resin composition is supplied from the first mixing portion to the second mixing portion (screw diameter: 180 mm), cooled to 190 ° C., extruded with a circular die (diameter 200 mm), and foamed to obtain a cylindrical foam sheet. rice field. At this time, immediately after being extruded from the circular die, cooling air (30 ° C.) was blown onto the inner and outer surfaces of the cylindrical foam sheet to cool it.
The cooled cylindrical foam sheet was torn along the extrusion direction to obtain a foam sheet having a foam magnification of 8.4 times (density 0.12 g / cm ³ ) and a thickness of 2000 μm.
The obtained foamed sheet was evaluated for odor and aggregation, and the results are shown in the table.
However, Example 3 is a reference example.

(Evaluation methods)
<Evaluation of odor>
The residual amount of normal butyric acid and N-butylformamide, which are offensive odor components derived from the polyphenylene ether-based resin, was measured by the following method.
Gas chromatograph mass spectrometry (GC / MS measurement) by the purge and trap (P & T) method was performed to measure volatile organic compounds generated when the foamed sheet was heated at a temperature of 250 ° C.
First, the foamed sheet was sliced thinly, 3 mg of this was precisely weighed, wrapped in aluminum foil, and set in a glass-lined stainless steel tube (GLT tube).
In this state, the GLT tube was heated at 250 ° C. for 3 minutes, and the generated gas was cold trapped in the cryofocus portion. Then, it was thermally desorbed and the volatile component was introduced into GC / MS.
The measurement conditions for GC / MS were as shown below. From the obtained chromatogram, the total ion chromatogram (TIC) peak area of each detected volatile component was obtained, and quantified by the following formula from the absolute calibration curve prepared in advance in terms of toluene.

Volatile component concentration (μg / g) = (area value of each component / area value of 1 μg of toluene) × 1 μg / sample weight (g)
In the above equation, the "area value of each component" is the TIC peak area of each detected volatile component.
In the above formula, the "area value of 1 μg of toluene" is the "TIC peak area of detected toluene (1 μg of toluene)" of the calibration curve in the following << method for preparing a calibration curve >>.

≪How to create a calibration curve≫
1 μL of 1000 ppm toluene standard solution was injected into a GLT tube, and measurement was performed under the following conditions. The TIC peak area (1 μg of toluene) of the detected toluene was obtained, and one inspection quantity line (straight line) was created.

≪GC / MS measurement conditions≫
·measuring device:
GC 7890A (manufactured by Agilent Technologies).
Mass spectrometer "JMS-Q1000GC" (manufactured by JEOL Ltd.).
-Column: ZB-1 (1.0 μm × 0.25 mm φ × 60 m: manufactured by Phenomenex).
-Column temperature: Hold at 40 ° C for 3 minutes, raise to 200 ° C at 15 ° C / min, raise to 250 ° C at 25 ° C / min, and hold at 250 ° C for 6.33 minutes.
-Carrier gas: helium (flow rate: 1 mL / min).
-Inlet temperature: 250 ° C.
-Interface temperature: 250 ° C.
-Detector voltage: -960V.
-Split ratio: 1/50.
-Ion source temperature: 250 ° C.
-Ionization current: 300 μA.
-Ionization energy: 70 eV.
-Detection method: Scan method (scan range: m / z 10-400).

≪P & T conditions≫
-Device: Thermal desorption device Thermal Desolution TD-4J (manufactured by Liquid Chromatography Science Co., Ltd.).
P & T conditions: PageTime (10s), InjectTime (20s), DesorbTime (180s), DelayStartTime (10s), DesorbHeather (250 ° C), CryoTempCating (200 ° C), CryoTempCooling (-40 ° C).

<Odor judgment>
Immediately after heating the thermoplastic resin foam sheet (10 cm × 10 cm) of each example in a hot air type constant temperature bath (150 ° C.) for 150 seconds, one appointed panelist confirmed the odor and evaluated it according to the following evaluation criteria.
≪Evaluation criteria≫
◎: Almost no offensive odor is felt.
〇: A slight offensive odor is felt.
×: A strange odor is clearly felt.

<Evaluation of productivity>
≪Pressure rise test≫
60 mesh screens were layered on both sides of a 200 mesh screen and these screens were attached to the breaker plate. This breaker plate was attached to the outlet of a single-screw extruder (caliber: 40 mm, L / D: 30 mm).
Then, only the resins of each example shown in Table 1 were charged into the single-screw extruder. The resin is melt-kneaded in a single-screw extruder at a resin temperature of 200 ° C. and extruded from a T-die (width: 120 mm, slit clearance: 0.8 mm) attached to the tip of the single-screw extruder at an extrusion rate of 5 kg / h. did. The pressure at the tip of the single-screw extruder was continuously measured with a pressure gauge, and the stable pressure was defined as the reference pressure P1 (MPa).
According to the formulation shown in Table 1, the resin and the inorganic particle group in each example were put into a single-screw extruder. In the same manner as when the reference pressure P1 was measured, 1 kg of the resin composition of each example was extruded, the pressure at the tip of the single-screw extruder was measured, and this was defined as the production pressure P2 (MPa).
The rising differential pressure ΔP (MPa) was calculated by the following formula. ΔP was classified into the following criteria and clogging was evaluated.
ΔP (MPa) = P2 (MPa) -P1 (MPa)

[Evaluation criteria]
⊚: ΔP is less than 1.5 MPa, no clogging is performed, and the productivity is good.
◯: ΔP is 1.5 MPa or more and less than 3, clogging is less likely to occur, and productivity is good.
Δ: ΔP is 3 to 7 MPa, and there is a slight concern about clogging.
X: ΔP is more than 7 MPa, there is a clear clogging, and there is a possibility that productivity may decrease.

<Evaluation of seat appearance>
The foam sheets of each example were visually observed and evaluated according to the following criteria.
〇: No dents extending in the MD direction are observed on the surface of the foamed sheet.
Δ: A slight dent extending in the MD direction is observed on the surface of the foamed sheet.
X: Concavities extending in the MD direction are clearly observed on the surface of the foamed sheet.

<Comprehensive evaluation>
A comprehensive evaluation was made according to the following evaluation criteria.
≪Evaluation criteria≫
A: Regarding the odor determination, the pressure rise test, and the evaluation of the seat appearance, all are "○" or "◎", and "◎" is two or more.
B: Regarding the odor determination, the pressure rise test, and the evaluation of the seat appearance, all are "○" or "◎", and "◎" is one.
C: The odor judgment, the pressure rise test, and the evaluation of the seat appearance are all "○".
D: Regarding the odor judgment, the pressure rise test, and the evaluation of the seat appearance, there is no "x", but there is a "△".
E: There is one or more "x" for odor determination, pressure rise test, and sheet appearance evaluation.

As shown in Tables 1 to 5, in Examples 1 to 16 to which the present invention was applied, the residual amounts of normal butyric acid and N-butylformamide were reduced, and the effect of the group of inorganic particles could be exhibited. In addition, in Examples 1 to 16, the results of the sensory odor determination were also good.
In addition, in Examples 1 to 16, ΔP was less than 3 MPa, clogging was less likely to occur, and productivity was good. Further, in Examples 1 to 16, the evaluation of the seat appearance was "◯".
In Comparative Example 1 in which the group of the first inorganic particles is not contained and the zeolite is contained as the group of the second inorganic particles, the productivity and the evaluation of the sheet appearance are both "x", and the aggregation of the inorganic particles is agglomerated. I couldn't suppress it.
In Comparative Example 2 which does not contain the first group of inorganic particles and contains synthetic silica as the second group of inorganic particles, the productivity and the evaluation of the sheet appearance are both “Δ”, and the residual normal butyric acid remains. The amount could not be reduced.
In Comparative Example 3 in which the hydrotalcite calcined product was contained as a group of the second inorganic particles without containing the group of the first inorganic particles, the productivity and the evaluation of the sheet appearance were both "x".
In Comparative Example 4 containing both hydrotalcite and zeolite, which are the second group of inorganic particles, the productivity evaluation was “x” and the sheet appearance evaluation was “Δ”.

Claims (9)

Has a foam layer,
The foam layer contains a thermoplastic resin and a group of inorganic particles.
The group of inorganic particles contains the first group of inorganic particles.
The average specific surface area of the group of the first inorganic particles is 1.0 m ² / g or more and less than 200 m ² / g.
In 50 to 100 parts by mass of the group of the first inorganic particles, the ratio represented by the mode diameter / median diameter of the primary particles is 0.1 or more and less than 1.0.
The content of the group of the first inorganic particles with respect to 100 parts by mass of the thermoplastic resin is 0.1 to 0.5 parts by mass.
The content of the first group of inorganic particles with respect to 100 parts by mass of the group of inorganic particles is 50 to 100 parts by mass.
Thermoplastic resin foam sheet. The thermoplastic resin foamed sheet according to claim 1, wherein the bulk density of the first group of inorganic particles is 0.02 to 1.0 g / cm ³ . The thermoplastic resin foam sheet according to claim 1 or 2, wherein the standard deviation of the median diameter of the primary particles of the group of the first inorganic particles is 0.3 μm or more. The thermoplastic resin foam sheet according to any one of claims 1 to 3, wherein the thermoplastic resin contains a polystyrene-based resin or contains a polystyrene-based resin and a polyphenylene ether-based resin. The thermoplastic resin contains a polyphenylene ether-based resin and contains
The thermoplastic resin foam sheet according to any one of claims 1 to 4, wherein the content of the polyphenylene ether-based resin is 10 to 50 parts by mass with respect to 100 parts by mass of the thermoplastic resin. The group of inorganic particles according to any one of claims 1 to 5, wherein the group of inorganic particles contains at least one selected from a bubble regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant and a deodorant. Thermoplastic resin foam sheet. The thermoplastic resin foaming according to any one of claims 1 to 6, wherein the content of the group of the first inorganic particles is 0.05 to 20 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Sheet. A molded product obtained by molding the thermoplastic resin foam sheet according to any one of claims 1 to 7. The molded product according to claim 8, which is a container for food.

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